68 ' BULLETIN OF THE BUREAU OF FISHERIES 



In our Bristol Bay data we can see occasional evidence of sudden, unexplained 

 fluctuations, which apparently have been reflected in later years. Perhaps the best 

 example of this is the sudden drop of 1919, which affected all the districts. The 

 fourth and fifth years before 1919 had. been exceptionally good on the Nushagak. 

 On the Kvichak the fourth preceding year had been below average but the fifth 

 had been excellent, and we have shown above that the highest correlation between 

 catches in this district is at five-year intervals. So far as the evidence of previous 

 catches goes, therefore, there was no reason to anticipate a poor catch in 1919. 

 Whatever the factors that caused this sudden fluctuation, the effect has been reflected 

 in a poor catch on the Nushagak in 1923 and again in 1927 and on the Kvichak in 

 1924. It seems probable that we have witnessed here the operation of just such 

 factors as we have been discussing, and that for some unknown reason one or more 

 of the spawning runs that were the parents of the run of 1919 failed to produce the 

 usual number of adult fish, and that this sudden fluctuation has tended toward the 

 production of cycles. The situation is extremely complex, of course, and we have 

 no way of telling how long these fluctuations (which appear to have been fixed by 

 the poor run of 1919) will persist. They may be distinguishable fur several cycles, 

 or they may have been obliterated already by factors about which we know nothing 

 and the effect of which we will not see until it becomes apparent in a modified run. 



With the data at hand we do not feel that it is possible to make any reliable 

 prophecy as to future runs. The probable errors of all our measures are large, and 

 there is always the chance that unusual circumstances may intervene to upset any esti- 

 mate that may be made. At present we know virtually nothing about these unusual 

 circumstances in the Bristol Bay region. Apparently they have operated in former 

 years to modify the runs very materially, and there is no reason to suppose that they 

 may not operate again and just as unexpectedly as they have in the past. In spite 

 of all this it seems desu-able to review what evidence we have and to point out certain 

 indications as to the future. 



In the Nushagak region we have had a general decline in abundance, as indicated 

 by the trend. It has been shown also that the short-time fluctuations here are at four- 

 year intervals at present. The run of the coming season (that of 1928) should bear a 

 general relationship to the run of 1924, therefore, which was one of the poorest in 

 recent years. . The run of 1923 on the Nushagak River was exceedingly poor also, so 

 that we can expect no marked effect in 1928 due to five-year fish derived from that 

 year. On the other hand, we have some evidence that in spite of a poor catch the 

 spawning escapement of 1924 was better than usual. The report of observers on 

 the spawning grounds in Wood River states that the escapement to that river was 

 "the most satisfactory for the last several years." ^ Nothing is known, however, 

 of the escapement to the other spawning regions in the Nushagak district. Except 

 for this meager evidence of a good spawning escapement, then, all indications point 

 toward an unfavorable year at Nushagak, possibly as bad as 1927. Knowing the 

 present depleted condition of this district, it would seem to be the part of wisdom 

 to reduce the intensity of fishing as far as possible. Even if a fairly good run should 

 develop, it does not seem at all likely that it will approach the magnitude of the runs 



» Alaska Fishery and Fur-Seal Industries in 1924. By Ward T. Bower. Appendix IV, Report, U. S. Commissioner of 

 Fisheries for 192& (1928), p. 99. Washington. 



